Optically transparent conductors have been utilized in industry mainly for displays for televisions, electronic handheld information device (e.g. Personal Digital Assistant or “PDA”), computers, iPods, smart phones, cellular phones, etc. Indium Tin Oxide (ITO) is the current standard with ITO coated on glass having a sheet resistance of approximately 5 to 8 ohm/sq. ITO on plastic for flexible devices is problematic, having a much higher sheet resistance of 50 ohm/sq. Many global industries have been looking for replacements, with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) being one potential. One approach to get high conductivity and low sheet resistance PEDOT requires sulfuric acid washing to remove the PSS template. This is an additional step to the process, and the resulting sheet resistances are not low enough to be competitive, having electrical conductivities of approximately 4500 S/cm with sheet resistances of 50 ohm/sq.
Other technologies include the use of carbon nanotubes, graphene, silver nanowires, etc. Each of these has its own problems. For carbon nanotubes it is the expense and supply of the carbon nanotubes, as well as lack of batch to batch consistency. For graphene, the problem has been processing to generate single to double layer films to achieve the transparency on bulk substrates. Silver nanowires have been most promising, but silver has a very low oxidation potential.
Thus, there remains a need in the art for new materials that can function as ITO replacements and that can be manufactured simply to result in films of high conductivity, low sheet resistance, and high transparency.